Kotlin supports nullability as part of its type System. Well, Enter Kotlin! Nullability and Nullable Types in Kotlin Wouldn’t it be nice if we could detect possible NullPointerException exception errors at compile time itself and guard against them? NullPointerExceptions are Runtime Exceptions which are thrown by the program at runtime causing application failure and system crashes. If you have been programming in Java or any other language that has the concept of null reference then you must have heard about or experienced NullPointerException in your programs. Sir Tony Hoare, The inventor of null reference This has led to innumerable errors, vulnerabilities, and system crashes, which have probably caused a billion dollars of pain and damage in the last forty years. But I couldn’t resist the temptation to put in a null reference, simply because it was so easy to implement. My goal was to ensure that all use of references should be absolutely safe, with checking performed automatically by the compiler.

At that time, I was designing the first comprehensive type system for references in an object oriented language (ALGOL W).

It was the invention of the null reference in 1965. Nullable Types and Null Safety in Kotlin Rajeev Singh Kotlin Febru5 mins read

Kotlin do if not null